A dispensing cartridge for caulking compounds, sealants, adhesives and other similar coating materials typically includes a hollow elongated tubular container for confining the material and a tapered nozzle serving as a port for dispensing material from the container. The nozzle is fixed to an end cap that is attached to one end of the container. A plunger is positioned at an opposite end of the container with the material disposed between the end cap and the plunger. To dispense material from the cartridge, the tip of the nozzle typically is cut off at an angle and pressure is applied to the plunger using a conventional caulking gun, or similar mechanism, causing the material to flow out of the nozzle to the adjacent surfaces to be caulked or sealed.
In manufacturing, the cartridge is filled with material once the top end cap is affixed at one end of the container. Next, the plunger and a ring seal are inserted into the container. The ring seal abuts an inner circumferential surface of a skirt of the plunger, the skirt being an axially extending annular portion of the plunger. The ring seal extends axially beyond a second end of the tubular container, the second end being opposite the end where the nozzle and end cap are attached. The ring seal is deformed, e.g. crimped, around the second end of the container to retain the plunger. Upon completion of the manufacturing process the ring seal prevents movement of the plunger in an axial direction away from the first end while allowing the plunger to move towards the top end cap when pressure is applied to the plunger.
Attaching the ring seal to the tubular container requires a complex process that involves rotating the tubular container. This rotation results in a vortex being formed in the material already in the container which results in an air gap in the container after the plunger is installed. This air gap is undesirable because the entrained air causes material to continue to flow out of the cartridge after the user of the caulking gun has tried to stop the flow of material. Also, since the ring seal attaches around the lower end of the tubular container, if the cartridge is dropped, then the second end, i.e. the end with the ring seal, deforms along with the ring seal. This deformation of the second end of the container inhibits the insertion of the push rod of the conventional caulking gun. Furthermore, readjustment of the ring seal to allow insertion of the push rod of the caulking gun is quite difficult.
As opposed to using a ring seal to limit axial movement of the plunger away from the top end of the tubular container, another method for retaining the plunger includes rolling the lower edge of the tubular container over thus decreasing the diameter of the lower end of the tubular container. This smaller diameter portion limits axial movement of the plunger away from the upper end while allowing movement of the plunger towards the upper end of the container. By only rolling over the lower edge of the container; however, the plunger is not sufficiently pushed towards the upper end of the tubular container to protect it from damage that may occur if the cartridge is dropped. Furthermore, simply rolling over the lower edge of the tubular container does not provide a very secure arrangement for containing the plunger. Additionally, by only rolling over the lower edge of the container, achieving a coplanar edge on which the plunger can rest is difficult.